A diffusion transfer heat-developable photographic light-sensitive material is known in this field. For the heat-developable photographic light-sensitive material and its processing method, reference can be made, for example, to Shashin Kogaku no Kiso (Base of Photographic Engineering), Edition of Nonsilver Photography, pp. 242-255; Corona, 1982.
Also, many methods for obtaining a color image by heat development have been proposed. For example, U.S. Pat. Nos. 3,531,286, 3,761,270 and 4,021,240, Belgian Pat. 802,519, Research Disclosure (hereinafter abbreviated as "RD"), September 1975, pp. 31-32, etc. propose a method for forming a color image by the combination of an oxidized product of a developing agent and a coupler.
However, since the foregoing heat-developable photographic light-sensitive material on which a color image is formed is of nonfixable type, silver halide remains even after the formation of an image, causing a serious problem of coloring on the white ground when exposed to strong light or after prolonged storage. Further, the foregoing methods are disadvantageous in that they normally require a relatively long period of time for development and the resulting image exhibits a significant fog and a low density.
In order to overcome these difficulties, an approach has been proposed which comprises imagewise forming or releasing a diffusive dye by heating, and then transferring the diffusive dye to an image-receiving material having a mordant with a solvent such as water (see U.S. Pat. Nos. 4,500,626, 4,483,914, 4,503,137, and 4,559,920, and JP-A-59-165054 (The term "JP-A" as used herein means an "unexamined published Japanese patent application")).
In the foregoing approach, a high development temperature is still required, and the preservability of the photographic light-sensitive material is still insufficient. Accordingly, an approach is disclosed which comprises heat development of a photographic light-sensitive material in the presence of a base or base precursor and a slight amount of water, and then transferring the resulting dye to provide acceleration of development, lowering of development temperature and simplification of processing in JP-A-59-218443, JP-A-61-238056, and JP-A-62-129848, and European Patent 210660A2.
Many methods for obtaining a positive color image by heat development have been proposed. Among these methods is an approach proposed in U.S. Pat. No. 4,559,290 which comprises heat development of a photographic light-sensitive material in the presence of an oxidizing type DRR compound having no capability of releasing a dye and a reducing agent or precursor thereof so that the reducing agent is oxidized depending on the exposure of silver halide and the oxidizing type DDR compound is then reduced by the reducing agent left unoxidized to release a diffusive dye. Further, U.S. Pat. No. 4,783,396 and JP-A-64-13546 disclose a heat-developable color photographic light-sensitive material comprising a nondiffusion compound which undergoes reductive cleavage of N-X bond (wherein X represents an oxygen atom, nitrogen atom or sulfur atom) to release a diffusive dye as a nondiffusion compound which releases a diffusive dye by the same mechanism as mentioned above. This process comprises exposing a multi-layer heat-developable color photographic light-sensitive material having at least a light-sensitive silver halide, a binder, an electron donor and/or precursor thereof (preferably nondiffusive), and a compound which is nondiffusive itself but undergoes reduction to release a diffusive dye on a support to light, and then heating the heat-developable color photographic light-sensitive material so that the electron donor is oxidized depending on the amount of the silver halide and the reducible dye-providing compound is reduced by the electron donor left unoxidized to release a diffusive dye which is then transferred to a dye-fixing (image-receiving) material comprising a mordant to form a positive color image.
An ordinary silver halide color photographic material has a multi-layer configuration. An example of such a multi-layer configuration comprises a panchromatic silver halide emulsion layer sensitive to red light, an orthochromatic silver halide emulsion layer sensitive to green light, and a regular silver halide emulsion layer sensitive to blue light as an uppermost layer coated sequentially on a support.
The foregoing color photographic light-sensitive material comprises panchromatic and orthochromatic silver halide emulsions which have been spectrally sensitized with an optical sensitizer generally referred to as "sensitizing dye". However, these emulsions also have blue-sensitivity characteristic of silver halide, causing color turbidity or color loss due to overlapping of spectrum and hence impairing color reproducibility.
In order to cope with the foregoing difficulty, a color negative photographic light-sensitive material normally comprises a blue light-absorbing filter layer provided interposed between a blue-sensitive silver halide emulsion layer and a green-sensitive silver halide emulsion layer. As such a blue light-absorbing filter layer, a layer comprising a silver colloid having a grain diameter of about 0.001 to 0.05 .mu.m or a layer comprising a dye or dyestuff which elutes with a processing solution or discolors during development as disclosed in U.S. Pat. Nos. 4,948,717, 4,948,718, 4,940,645, and 4,900,653 is used.
In a heat-developable color photographic light-sensitive material comprising a dye-providing compound which is colored, the layer containing such a dye-providing compound serves as a filter layer itself. Accordingly, such a heat-developable color photographic light-sensitive material does not necessarily require another blue light-absorbing filter layer. However, if the dye-providing compound is a colorless coupler or if the absorptivity coefficient of the heat-developable color photographic light-sensitive material at 500 nm or less is insufficient, it is preferable that a blue light-absorbing filter layer be provided.
Nevertheless, the heat-developable photographic light-sensitive material cannot comprise a silver colloid layer as mentioned above. This is because the heat-developable photographic light-sensitive material encounters a phenomenon in which colloidal silver serves as a physical development nucleus, resulting in aggravation of fogging, density drop or color turbidity.
Further, it is undesirable to use a dye or dyestuff which elutes with a processing solution or discolors during development in the heat-developable photographic light-sensitive material. That is, since the heat-developable photographic light-sensitive material is developed in a short period of time, such a dye or dyestuff cannot be sufficiently discolored or is transferred to the image-receiving material causing color stain.
JP-A-60-209734, JP-A-61-159645, and JP-A-2-271353 disclose a blue lights absorbing dye for use in a heat-developable photographic light-sensitive material. However, this blue light-absorbing dye is insufficient in the requirements that it should be prevented from being diffused into other layers during simultaneous multi-layer coating or storage and should not stain the image during heat development or heat transfer.
On the other hand, the incorporation of a colored solid pigment such as cadmium yellow in the silver halide emulsion layer and/or its adjacent layers in a heat-developable color photographic light-sensitive material is disclosed in JP-A-61-20943, and JP-A-1-167838. However, the object of this approach is to enhance sensitivity and to improve S/N ratio and the preservability of a raw photographic light-sensitive material. Accordingly, this approach does not necessarily provide a satisfactory blue light-absorbing filter. Further, in a color image formation process which comprises imagewise exposing a heat-developable color photographic light-sensitive material to light, subjecting the heat-developable color photographic light-sensitive material to heat development in the presence of a small amount of water and a base precursor, and then transferring a diffusive dye thus produced or released to an image-receiving material, if the base precursor is a combination of a scarcely water-soluble basic metal compound and a compound capable of undergoing a complex compound formation reaction with metal ions constituting said basic metal compound in the presence of water as a medium (complexing agent), an inorganic solid pigment, if used, reacts with the complexing agent to produce a water-soluble colored material which is then transferred to the image-receiving material to cause color stain or produce a substance that adversely affects the photographic properties.